Abnormal glucose tolerance and insulin resistance are related to multiple cardiovascular risk factors especially reduced HDL, elevated serum triglycerides and hypertension (Liese et al. (1998)). When clustered these is abnormalities increase the risk of coronary heart disease (CHD) morbidity and mortality, an effect that is independent of other conventional risk factors (Trevisan et al. (1998)). Co-ocurrence is usually present in insulin-insensitive individuals (Himswarth (1936)) and is often described in relation to visceral adiposity (Haffner et al. (1986)) and lack of physical activity (Helmrich 1991)). The estimated prevalence ranges from 3% (Trevisan et al. (1998)) to approximately 30% (Liese et al. (1998); Reaven (1994)) depending on how this insulin resistance-dislipidemic syndrome is defined and in which population it is measured.
Hyperglycemia and diabetes are strong and independent risk factors of both all-cause and cardiovascular (CVD) mortality (Wing et al. (1998)). These links are more pronounced when the diabetes is associated with other unfavorable risk factors such as hyperlipidemia (Goldsmith et al. (1994)), hypertension (Burt et al. (1995)), or a cluster of metabolic disorders (Stamler et al. (1993)). Since people with diabetes have almost twice the risk of dying from CVD (69.6%) compared to people in the general U.S. population (Gu et al. (1998)), the control of high glucose levels and other concomitant coronary heart disease (CHD) risk factors represents the most effective approach to prevention (Savage (1996)). The importance of stronger nutrition-hygienic measures has been stressed repeatedly for the public at large (Stamler et al. (1993); National Cholesterol Education Program: Second report of the expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (adult treatment panel II). Circulation. 1994; 89:1333-1445)). When these measures prove inadequate, an aggressive drug therapy is often required to meet the conventional treatment guidelines (National Cholesterol Education Program: Second report of the expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (adult treatment panel II). Circulation. 1994; 89:1333-1445)). In the general population, this approach has been shown to be effective in lowering both the prevalence of hypertension (Burt et al. (1995)) and serum cholesterol levels (Johnson et al. (1993)), but has not reduced the incidence of diabetes (Harris et al. (1998)).
Although it has been extensively described (Liese et al. (1998); Trevisan et al. (1998; Himswarth (1936); Haffner et al. (1986); Helmrich et al. (1994)), followed-up (Reaven (1994)), and had its prevalence determined (1,2), no specific recommendations for treatment of this syndrome have been proposed by health agencies. In practice, initial therapy of individual risk factors such as moderate dyslipidemia, hypertension or hyperglycemia is nonpharmacological. Treatment will often include behavioral changes to reduce body weight, increase physical activity, and moderate alcohol consumption. To achieve nutritional goals, there are three main approaches: a high-carbohydrate/low-fat diet (National Cholesterol Education Program: Second report of the expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (adult treatment panel II) Circulation 89:1333-1445 (1994)), sharing calories between monounsaturated fat and complex carbohydrate at the expense of saturated fat (American Diabetes Association (ADA): Nutrition Recommendations and principles for people with diabetes mellitus. Diabetes Care 22:s42-s43 (1999)), or supplementing a high-carbohydrate/low-fat diet with exercise (Stefanick et al. (1998)).
Tighter fasting and postprandial glycemic control results in a considerable reduction in CHD and all-cause mortality (Wei et al. (1998)), as well as fewer long-term microvascular complications both in type 1 (DCCT Research Group: The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The diabetes control and complications trial. New Engl J Med 329:997-986 (1993)) and type 2 diabetes (UK Prospective Diabetes Study (UKPDS) Group: Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes: UKPDS 34. Lancet 352:854-865, 1998). Effective dietary strategies shown to decrease plasma glucose excursions include the use of high fibre and low glycemic index diets (Wolever et al. (1992); Jenkins et al. (1994)). The mechanism is presumed to involve slowing carbohydrate absorption (Jenkins et al. (1994)). Based on recent population studies these types of diets have been shown to have a protective role in preventing diabetes (Salmeron et al., Diabetes Care 20:545-550 (1997); Salmeron et al., JAMA 277:472-477 (1997)) and CHD (18). In the case of clinical studies however, it is the viscous water-soluble fibers, which increase the viscosity of digesta in the human gut (Eastwood et al. (1992)) that reduce glucose and lipid CHD risk factors (Anderson et al. (1986)). Whether soluble fibre is able to reduce a cluster of risk factors is speculative. Studies using soluble fibre as an adjunct to conventional treatment in individuals with two or more major CHD risk factors are scarce (Uuistupa et al. (1984)).
Evidence suggests that fibre may also be used in a therapeutic role. Recent epidemiological findings confirm the relationship between high dietary fiber intake and lower risk of developing both diabetes (Salmeron et al. (1997); Salmeron et al. (1997)) and CHD (Rimm et al. (1996)). Soluble dietary fiber, in particular, has been shown clinically to reduce the need for insulin, (Landin et al. (1992)) improve glycemia (Aro et al. (1981)), and reduce serum LDL-cholesterol (Brown et al. (1999)). Its viscosity is proposed as an important mechanistic factor (Jenkins et al. (1978)). However, to date, there is no clearly effective composition or method for reducing blood glucose.